Device for demonstrating the circuits and fields of electrical motors and generators



Aug. 15, 1950 G. w. THOMPSON 2,518,506

DEVICEFOR DEMONSTRATING THE CIRCUITS AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 I 11 Sheets-Sheet l 8 "PHASE Ll/VE I INVEN TOR. Geo/ye W Thompson A ZZORNEY.

Aug.,l5,1950 V G w THOMPSON 2,518,506

DEVICE FOR DEMONSI'I'RAITING THE CIRCUITS AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 11 Sheets-Sheet 2 1 Q :2 :20 C) o '0 o o a o O b N) VO O O O o O o o o o O O o o o 0 Q o 1N VEN TOR. Geo/ye W Thompson A rroRALX Aug. 15, 1950 a. w. THOMPSO DEVICE FOR DEMONSTRATING N 2,518,506 THE CIRCUITS AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 ll Sheets-Sheet 3 A TTUEA/EY Aug. 15, 1950 Filed Dec. 14, 1945 OF ELECTRICAL MOTORS AND GENERATORS 11 Sheets-Sheet 4 INVENTOR. Gearye W Thompson A TTOIFA/EP.

Aug. 15, 1950 G. w. THOMPSON 2,518,

DEVICE FOR DEMONSTRATING THE cmcurrs AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 11 Sheets-Sheet 5 INVEN TOR.

Gearye 14! Thompson BY A TTORNEY.

. 2,518,506 DEVICE FOR DEMONSTRATING THE CIRCUITS AND FIELDS Aug. 15, 1950 G. w. THOMPSON OF ELECTRICAL MOTORS AND GENERATORS ll Sheets-Sheet '6 Filed Dec. 14, 1945 .INVENTDR. 650m:- 144 THOMPSON A T TOAWEY Aug. 15, 1950 G. w. THOMPSON 2,518,506

DEVICE FOR DEMONSTRATING THE CIRCUITS AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 11 Sheets-Sheet 7 4 /72 O n i O o O 0 5 0 0 O O /75 O ,2 O O 0 /7a 0 [75 0 L 0 O 0 I O c O 02 O O O 172 a O O O O O I O INVENTOR.

O Q O O 650/951? M. Tara/wavy BY Fr u Aug. 15, 1950 s. w. THOMPSON 2,518,506

DEVICE FOR DEMONSTRATING THE CIRCUITS AND FIELDS I OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 11 Sheets-Sheet a 1N VEN TOR. GEORGE W THOMPSON BY W A Tram 5x Aug. 15, 1950 G w. THOMPSON 2,518,506 DEVICE FOR DEMONSTRATING THE CIRCUITS AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS Filed Dec. 14, 1945 11 Shets-Sheet 9 V IN VEN TOR. 650/?55 W THOMPSON ATTOR/VEX 4 Aug. 15, 1950 G. w. THOMPSON DEVICE FOR DEMONSTRATING THE cmcurrs 2,518,506 AND FIELDS OF ELECTRICAL MOTORS AND GENERATORS l1 Sheets-Sheet 10 Filed Dec. 14, 1945 Aug. 15, 1950 G. w. THOMPSON 2,513,506

DEVICE FOR DEMONSTRATING THE CIRCUITS AND FIELDS I OF ELECTRICAL MOTORS AND GENERATORS Filed Deb. 14, 1945 11 Sheets-Sheet 11 7 u m v "a w w a R u 3 E g MVH- w o a g a "a 1 9 g; KO N $3; 8 a; Q Q $.B 5.!

N 3 R3 3 Q N INVENTOR.

George W Thompson BY W i atented Aug. 1950 UNITED PATENT 'FI CE :2,518,5.06 DEVICE, Foe 'nnMous'rnnrrNe THE cmoorrs ANDFIEIJDS or ELECTRICAL M0- T-oRs AND- GENERATORS George W. Th0mI)S0l1, UnitedlStates Navy -"Applica'tion December 14, 19i5gSerial Nm 635,137

wsolaims. (o1. 19) (Granted un'derthe act 61' March 3,-1883,as

The present. invention relates to educational ..devices and concerns specifically visual training .aids for use inproviding visual representation of concepts that are intangible and not capable of Sensory perception.

It is found in educational programs. involving instruction in subjects relating to concept'sithat .are intangible and notsubject to. sensory pereption'that considerable difficulty'isencountered by instructors in presienting, and by students in co rnprehending, such concepts. Thus,, in .educaiitional'programs involving the study of. electricity and magnetism, considerable difficulty i'sienlcountered. in presenting instruction involving such intangible concepts as .magnetic force, voltage,

current flowand the phenomenonof induction.

conductor, and While thephenomenonofinduc- .ztionitself is not capable of being observed directly it can be detectedbythe effect produced when ithevoltage. is induced; for examplelby the visual iefiectproduced on a galvanometer connectedto the conductor.

"Instruction regardingelectro-mechanical inter- :converters su'chas generators and .motors for "inter-converting mechanical energy and electrical .energy is facilitated by .use. of training aidsthat visualize the intangible concepts .involved. "For this purpose, charts and diagrams, often employ- 111g color, and other visual representations, are

used to"illustrate the electrical and magnetic "phenomena involved. Also employed are mock devices that simulate actual machinessuch as generators 'or motors and that are activated mechanically 'or otherwise tofillustratewisiially the phenomenon involved. While such;devices "are often helpful, experience has shown that;im-

provement is desirable to provideaidevice'gthat simulates closelythe tangible parts of the device to be illustrated and afiords a cleanvisualrepre- 'sentation of the intangible factors-involved.

"the educational device of this invention-is adaptable to many different uses but has been shown for convenience as a training aid for-use 'in instruction concerning; a multiphase alternating-current generator and a multiphase alternating-current motor. "Each device can loe used independently for i'demonstration purposes "or both I can be ;used- :in combination for demonstratinggenerator andmotor operation; Me-

-ameriddi8piil 30, 1928; 3'70 0. G. 757) .2 chanical parts of a. conventionalgenerator and a conventional motor ,of this type are reproduced independently, in simplified form for the sake .of clarity.

"The mock generator .consists principallyofla stationary. transparent faceplate symbolizing, a

stator, and an opaque disc mounted for rotation centrally in front, of the faceplate and symbolicin a two-pole rotor. .Magneticlines of..for ce and ,electricalwindings are shown graphically 'on thejapaquc-z rotorby conventionalelectrical symbols (hereinaftercalled fsYmbolsfU together with symbols indicating. .the two. poles. 7 Symbols ,on

the vvtransparent stator represent .niultipliase iwindin-gs. .Lighting means 1are.provided behind the transparent stator: multiphase windings and arranged :so. that with ,the rotorminranygiven position the illumination of the windings simuplates the instant electrical conditions that pre- Vail ;in the, correspondingwindings of an actual generator. Intensity of thelight that illuminates :any; particular'winding indicates-the intensity .wi th which an actual winding is energized -.electrically by induction; andvcolor of the-lightindicates the instant polarity of such- "energization 'induced-in-the winding. fThiS deviceis arranged so that the rotor canwbe-arrested in any given :position to showinstant conditionsin the various windings, or so :that the'pqrotor canbe'turneduto represent the progressivelyuchanging conditions .thatwoccur in the-various windings during; operation of an actual generator. Separate phase windings canabe illuminatede-individually tosim- :plify the study :ofwa:singlephase, or the various windings can be illuminated for study :ofz'zthe -relationship-between:phases.

.The mockmotor is similar to the mock generator exceptthat parts are constructed to illustrate a motor of either the synchronoussorinduction type. -Thernockzm'otor consistsyprincipallyiof a stationary transparent faceplate representing- .a

"(four-pole stator and a pair of opaque discs mount- ;led fonrotation centrallyin front of therfaceplate and designed for alternative use. 1One'.of:ithe

6 discs. is. designed to represent. a ,synchronousstype rotor and symbols representing rotor-windings andithe':four poles are provided. Theotheridisc fi'eldrin the stator and the. induction rotor can be demonstrated. The lighting system for illuminatin'gthe stator windings is similar-'tothel-lighting system for the mock generator, but is adapted for the four-pole motor construction.

One object of the invention is to provide an educational device that affords an activated visual representation of concepts that are intangible and incapable of sensory perception.

Another object is to provide an education device for instruction in electro-mechanical interconverters in which an activated visual indication of intangible electrical and magnetic phenomena is provided.

Another object is to provide an educational device in the form of a mock multiphase alternating-current electro-mechanical interconverter in which represented electrical windings are arranged for illumination so that intensity of illumination simulates intensity of energization of the windings, and color of illumination simulates the polarity of energization.

Another object is to provide an educational device in the form of a mock multiphase alternating-current electro-mechanical interconverter in which represented electrical windings are arranged for visual activation to simulate electrical conditions within the windings, and in which the rotor can be arrested to simulate instant conditions in the windings or can be rotated to simulate progressively changing conditions, and in which separate phase windings can be activated individually or collectively.

Another object is to provide an educational device in the form of a mock multiphase alternating-current generator and an independent mock multiphase alternating-current motor in each of which represented electrical windings are arranged for visual activation to simulate electrical conditions within the windings, and in each of which the rotor can be arrested to simulate instant conditions in the windings or canbe rotated to simulate progressively changing conditions, and in each of which separate phase windings can be activatedindividually or collectively, the mock generator and mock motor being adaptedfor use together for demonstrating generator and motor operation.

Further objects and advantages of this invention, as well as'its construction, arrangement and operation, will be apparent from the following description and claims in connection with the accompanying drawings, in which Fig. 1 is a front elevational view of a preferred form of the invention embodying a mock multiphase generator;

Fig. 2 is a side view, partly in section and partly in elevation of the construction shown in Fig.'1;

Fig. 3 is a front elevational view with the cover removed of the construction shown in Fig. 1, illustrating the arrangement of lights and compartments therefor;

Fig. 4 is an enlarged sectional view along line 44 of Fig. 3;

Fig. 5 is an enlarged view in section showing. the switching arrangement for controlling the color of lights;

Fig. 6 is a view approximately along line 6-8 of Fig. 5;

' Fig. 7 is an electrical wiring diagram for the mock generator;

Fig. 8 is a front elevational view of a further embodiment of the invention showing a mock multiphase motor;

Fig. 9' is a side view partly in section and partly in elevation of the construction shown in Fig. 8;

, Fig. 10 is a plan view of a detachable mock I synchronous rotor for use in connection with the embodiment of the invention illustrated in Figs. 8 and 9;

Fig. 11 is a front elevational view with the cover removed of the construction shown in Fig. 8 illustrating the arrangement of lights and compartments therefor;

Fig. 12 is an enlarged sectional view along the line I2-l2 of Fig. 11;

Fig. 13 is an enlarged sectional view through the main shaft showing the mounting of the rotor discs;

Fig. l4 is an enlarged sectional view showing the clutching arrangement used in connection with the Selsyn transmitter;

Fig. 15 is an electrical wiring diagram for the mock motor; and

Fig. 16 is a wiring arrangement adapted for use in conjunction with the wiringarrangement shown in Fig. 15.

Similar .numerals refer to similar parts throughout the several views. A mock generator 10 having a framework ll including a box I2 with a top I3, bottom l4, side's I5 and a back 16 is provided with a vertical reinforcing member I! (see Figs. 1 and 2). These members may bx. made of wood or similar material. A cover-plate I8 is provided and is formed from transparent material such as Plexiglas. Box I2 is supported upon vertical legs l9, which are reinforced by cross-braces 20, and each leg is secured by means of anchor members 2| to a platform 22 supported upon casters 23, which render framework 'll movable.

Mounted for rotation in front of cover-plate l 8 (Fig. 5) is a disc 24 of Bakelite or other opaque material, which is secured by screws 25 to a support disc 26 having a hub 21 adapted to be held by a screw 28 to one end of a shaft 29. Shaft 29 is mounted for rotation in box [2 and is supported adjacent its rear end by a bearing 3|], which is secured to back-reinforcing member IT by screws 39', and at its other end is supported by a bearing 3|, which is secured to cover-plate Is by screws 3|. A thrust collar 32, secured to shaft 29 by set-screw 33, in combination with hub 21 of support disc 26 prevents lateral displacement of shaft 29 relative to cover-plate 18 of box l2. Mounted upon shaft 29 at the .rear extremity thereof is a sprocket wheel 34 having an integral hub 35, which is locked to shaft 29 by set-screw 36.

Rotary disc 24 is designed to represent the twopole rotor of a multiphase alternating-current generator while cover-plate I8 is designed to represent the stator of such a generator. Symbols representing electrical windings 31 (see Fig. 1) are painted or otherwise depicted on opaque rotor 24 and positive and negative symbols at the ends of windings 3! represent relative direction of current; flow therein. Symbols representing magnetic lines of force are shown visually at 38. To simplify the illustration, aQnorth magnetic pole is indicated .by the letter N and a southv magnetic pole is indicated by the letter .S. Windings 31 and magnetic lines of force 38 afford a visual simulation of the electrical and magnetic conditions that prevail in the two-pole rotor of a generator designed to be excited by direct current.

Preferably, transparent cover-plate I8 is painted with opaque material such as black paint except for symbols representing electrical windings 39, which are designed to represent threephase windings and which, because of their transparency, can be illuminated by lights 10- suitable material. it three individual selector switches 54A, 54B'and spectively (Fig. '7).

rates within box 1 2 and" hereinafter described.

be additive, windings 4 9A and'MIA are joined together in series with reverse connections byia represented conductor 41. The 40B andidflB and also ABC and 40C windings'of each of the *other two phases are likewise connected together in reverse. -Windings (MA and 40A, 40B and 40B, and 400 It is then "seen that each .pairxof and 40C) represents onecomplete phase winding. The free ends of windings 40A, 40B. and 40C represent the three phase leads from the generator, as indicated by legends'inscribedon cover-plate it, while theiree ends of windings 40A, 49B and MC are connected together'to a common represented conductor 42 to illustrate the standard WYE connection.

Phase windings 49A, 40B and 400 are adapted for illumination by three sets of lights 43 (Figs.

3 and 4) located within box I2, while windings 30 40A, 46B and liiC' are adapted for illumination by three additional sets of lights 44 located within box l2. Alternate lights in each of rings 43 and 44 are red, whilethe lights in between aregreen. The two colors are used to indicate the relative polarity of simulated induced voltage in windings 39. In a manner hereinafter described, the red and green lights are arranged tobe illuminated independently. The lights are mounted in wet est-streets. 'Roller some 6| aremounted upomd-iscil facingiJplate 53. .'.'Each' of rollers :50

--and*6l :is'supported.for rotation upon a stud 62,

rw-hichis threadedlinto plate 5Lcat 63. A thrust .i-iwasheri 154 secured toistud .62 by a screw 65 re- -ita'ins each of rollers '60 and GI in place. Rollers BO-JiandFGIuare disposed 180 apart upon disc 51 .::and roller460xis1disposed at agreater radial distance from shaft 29 than is roller 6|. Roller '60 is locatedso that as it passes switch EAAit trips switch toggle blade 55A thereof inwardly toward -shatt2 9; while" movement of roller 6! past switch =54A-causes tripping of switch toggle-blade '55A there'of 'outwardly. :Switches 54B and 540 are e -activatedsimilarlyby rollers '60 and 6|. :Elec- :tri'cal connections for switches 54A; 54B and 54C wlll be hereinafter described in connection with Fig.7.

r A.-handwheel =56 (Figs. 1 and 2). provided with a citankrhandle 6! is mounted in a lower corner of cover-plate [3 for rotation of a shaft 68. -:Shaft 68' is supportediadj acent one end for rotation relative to cover-plate l8 by bushing BSand :is supported adjacent its other end forrotation relative torear plate 16 by means of bushing H.

Asprocket: wheel IZiSsecured to the rear ex- :tremity of shaft 68.

'Mounted'upon bottom plate I4 in-one corner of box I2 is a Selsyn'transmitter 13' of conventional type, said transmitter having a rearward- -.ly-ex:tending rotor shaft '14 upon which is mounted asprocket 'wheel l5. Sprocket wheels 15 12. and-34 are coupled by a sprocket chain :16. Rotation: of hand wheel 66 thus causes ro- 35 tation' of disc 24- and Selsyn transmitter rotor :shaft 14. Disc 24 and Selsyn transmitter rotor 'shaft 1'4 are geared together in l-l ratio. Electricalrconnections which will now be described cause represented phase windings 39 on coverindividual sockets secured to the inside of qg p fle illuminated y the action of Selsyn cover-plate E8. The inside of cover-plate is divided into compartments by means of partitions 46, which are so designed thata separate compartment is formed behindeach ot the transmitter 13 in synchronization with rotation of disc 24.

Selsyn transmitter 13 is provided with. a two- .vpole rotor having winding '15 and is provided windings A, 49B, 400, 451A, 4913' and 4005 with a stator having three phase windings Partitions 45 are secured together 'by welding, the back is secured by means of screws 41 and nuts 48, and the whole assembly is secured to the rear of cover-plate i 8 by screws 49. The e1'ec 44 will be hereinafter described.

In order that the phase windings may beilluminated in synchronization with movement'of rotor 26, sequence switches 54 (Figs. 5 and 6) are arranged as follows: Mounted'uponthe'inside'of 5 back reinforcing member I! is a pair of parallel horizontal wooden blocks 59, which are secured in place by means of bolts 5! and 'nuts 52. Mounted on blocks 50 in spaced relation Sirom ='(seeFig. '7). Rotor winding 15 is excited by alwternating'current from any suitable source '(not shown) through conductors T3 and 14. Stator phase windings 15 are connected together. in

trical connections for illuminating lights 43: and 1:5 the-conventional Y arran entsyn transt'mitter '13 operates in effect as a transformer, with'rotor winding 15' serving as a primary and stator windings 15 serving as secondaries. The voltage induced in the individual stator windings 7 5 andiimpressed across leads 16, Hand 18 varies with the rotational position of rotor winding :15. -Leads 16, l1 and lii connect the Selsyn transmitter into the mock generator electrical "circuit in such maner that lights 43 and 44 (Figs.

back-reinforcing member I! is asupporting plate r 1 and 2) illuminate the individual represented 53, which can be formed ofmetal Or any other Mounted upon plate 53-are 54C which control alternatively selection of phase windings 39 with an intensity that varies .with thegsynchronized rotational-position of. disc 24 and Selsyn transmitter 13.

' The electrical connections by which Selsyn either red or green light illumination tOShOWiT-tT8JI1SD1itt8T13 (Fig.7) illuminateswinding 40A relative polarity of voltage induced-in windings 48A, 493, MC and 453A, 46B, 40C respectively. Switches 54A, 55B and 54C arespaced-in 120 angular relation, and are provided withtoggle blades 55A, 55B and 55C respectively, as well as' 7o nbla'de 82 anda contact 83.

contacts 86A, S'lA, 86B, 81B, 86C ancl 81C re- Switches 54A, 54B and-54C are secured to plate 53 by means of locknuts '56. T Mounted for rotation with shaft 29-is adisc- .withieither red or green light will now be dewscribed. Conductor 16 leads from Selsyn transimitter i'lii "to master switch BIA, which controls z -illumination of winding 40A and which has :a

Contact .83 is con- -.-nected. by-aconductor 84 to selector switch 54A having .toggle blade 55A and contacts 86A and 987A. Contact =86A isconnected. by conductor 88 "xtora ieederline 89 'for a setuof. red lights 91A,

.-plate 51 having ahub 58secured rigidly ztoshaft" -which' serve'.toilluminateewinding MIA iLE-ig..1)

.minal for Selsyn transmitter conductor Tl.

' to illuminate winding 40A.

*and form :part ofthe ring of lights 43. return line .02 is connected by means of a conductor 93 to master switch BIB, which also serves 'asa ter- Thus it will be seen that, with master switch 8IA closed and with selector switch 54A closed against contact 86A, a circuit is provided whereby Selsyn transmitter 13 illuminates .red lights 9IA to afford redillumination of winding 40A.

Contact 81A of switch 54A is connected by conductor 05 to a feeder line 96, and through a set of green lights 91A, which serveto illuminate winding 40A, to a return line. 98, conductor 99 and cross wire I toline 93, thence to master switch BIB, to which Selsyn-transmitter conductor I1 is connected. It will thus be seen that, with master switch 8IA closed and with switch 54A closed against contact 01A, a circuit is provided whereby Selsyn transmitter I3 illuminates green lights 91A to afford green illumination of winding 40A.

The electrical connections by which Selsyn transmitter I3 illuminates winding 40A with either red or green light will now be described. Conductor 88 from switch 54A is connected by a conductor ml with contacts I02 and I03 of a manual selector-switch I04A', which controls illumination of winding 40A. Switch I04A is provided with toggle-blades I05 and I06, which are locked mechanically for movement together by a tie-rod I01. Blade I00 is connected by a conductor I08 to a feeder line I09 for a set of red lights IIOA', which serve to illuminate winding 40A and form part of the ring of lights 44. A

return line III is connected by a conductor H2,

cross-line H3, cross-line I00 and conductor 93 to master switch 8| B. Blade I05 of switch I04A' is connected by a conductor II4 to a feeder line II5 for a set of green lights USA, which serve A return line H! is connected by a conductor H8 and cross-line H9, cross-line II3, cross-line I00 and conductor 03 to master switch BIB. Conductor 95 from switch 54A is connected by a conductor I20 to contacts I2I and I22 of switch I04A'.

It will be seen that if master switch BIA is closed and switch 54A is closed against contact 86A thereof to provide red light illumination of winding 40A, then manual selector switch I04A can be closed with blade I06 against contact I03 to provide red light illumination of simulated winding 40A through the circuits just described, so that windings 40A and 40A are both illuminated with red lights. On the other hand, if manual selector switch I04A is closed with blade I05 against contact I02, then green light illumination is provided for winding 40A through the circuits just described, and windings 40A and 40A are illuminated with lights of contrasting color.

It will also be seen that if master switch MA is closed and switch 54A is closed against contact 81A thereof to provide green light illumination of winding 40A, then switch I04A' can be closed with blade I05 against contact I2l to provide green light illumination of winding 40A so that windings 40A and 40A are both illuminated with green lights. On the other hand, if switch I04A is closed with blade I06 against contact I22, then red light illumination is provided for winding 40A, and windings 40A and 40A are illuminated with lights of contrasting. color.

The electrical system for providing red and green light illumination for windings 40A and -.40A', which constitute the A phase portion of 8 winding'39'repr'esented on'cover-plate I 8 (Fig. 1) have been described in detail. Similar electrical systems are provided, as shown in Fig. '7, for illuminating the B phase portions of winding 39 and include master switch 8IB, switch 543 having toggle-blade 55B and contacts 86B and 01B, switch I04B', red lights 9IB and H03, and

green lights 91B and H63 for controlling B phase illumination. Further included are master switch 8lC,switch 540 having toggle-blade 55C and contacts 860 and 81C, switch I 04C, red lights SIC and H00 and green lights 91C and I IBC' .for controlling C phase illumination. Electrical connections for the B and C phase are similar to connections for the A phase and are illustrated in detail in Fig. 7.

Operation of the device is as follows: The training aid is conditioned for operation by connecting Selsyn-transmitter winding 15 to a suitable source of alternating current by means of conductors I3 and I4.

The operator, in giving a demonstration, can then explain preliminarily the phenomenon of induction that occurs when there is relative motion between a magnetic field and a conductor that cuts the lines of force of the field, and can point out that the simulation of windings of the stator, represented by windings 39, correspond to the conductor, while the lines of force 38 on rotor '24 correspond to the magnetic field having a north pole N and a south pole S. It can be explained that the magnitude of the electrical efiect induced in stator windings 39 depends upon the number of turns or loops in windings 39, the number of lines of force in magnetic field 38, and the rate of relative movement or rotation of rotor 24. It should be emphasized that in an actual generator rotation of the rotor must occur in order to induce an electrical effect, but that the training aid, for purposes of illustration, is arranged so that even with rotor 24 arrested in a particular position, windings 39 indicate an induced effect so that instant conditions can be demonstrated. Attention can also be invited to the fact that rotor windings 3'! of an actual generator are connected to a source of direct current, as indicated by the and symbols on rotor 24.

Rotor 24 is now positioned as shown in Fig. 1,

with the north pole to the left, and master switch BIA is closed to condition windings 40A for illumination. Rotor 24 is then rotated clockwise through to simulate actual operating conditions, and the operator can call attention to the fact that, just as represented magnetic field 38 sweeps windings 40A, the magnetic field of an actual generator induces a voltage in its windings. The intensity of the voltage varies from zero at the start of the sweep to a maximum when the north pole is positioned vertically and decreases to zero at the end of the sweep because of the fact that the number of magnetic lines of force 30 that cut winding 40A vary from zero to a maximum and back to zero again. During the sweep a visual representation of the induced effeet is provided by red light illumination of winding 40A, and the intensity of the illumination varies from zero at the start of the sweep to a maximum and back again to zero at the end of the sweep. It can be explained by the operator that the variation of intensity in illumination is an indication of variation in intensity of the induced electrical voltage and that color of the illumination indicates the polarity of the induced effect, red illumination indicating polarity induced when'the rotor north pole sweeps a stator windingand .greenillumination. indicating. .op

posite polarity inducedrwhen. the rotor south pole:

sweeps-.astator winding,

The. red light illumination zduring. the 180.

sweep-is provided-bytheiollowing operation oh the .trainingaid: As described, master switchBlA. was closed manually... Switch 54A. is closed against cQntactBSAat-the beginningof-the sweep by movement of roller .6! past the-switch to--com.--

plete the circuit including and lightsBIA. adapted for illumination. of. winding. 40A.. Rotation ofrotor 24 through arlflll sweepcauses synchronized rotation of Selsynetransmitter' rotor-windingv whereby the voltage across. Selsyn-transmitter lines. '16 and TI isvariedirom zero toa maximum andback to. zero. to vary theintensity ofillumination. of red lights .91 A..

The demonstration can be-continuedby rotate ing..i.0t0r 24 through an. additional 1.808 sweep to. complete one. revolution; Duringthis sweep .the" rotor southpole sweeps winding. A and the windingwis illuminated'hwith green. light. representing the olarityof. the induced voltage. The

operator can. call .attention..to...the. contrast in. color of. illumination betweenred-and greencore- F responding. to the-contrastin..polarity of. induced. effect. when winding. 40A issweptlby anorth. meg netic pole anda. south. magnetic. pole. Green. light illumination. iii-winding. 40A is provided. since,..at the start of. the second 180sweep,.switch. .1

54A is closed against. contactv -81A=by .roller 6D to complete thecircuitincluding green lights 91A. As previously described,.rotation.of. Selsyn-transmitter. rotor-winding 1.5 causes variation. ofv in -.v

tensity of the illuminationof winding. 4.flA,-.and-

il'lustratesvariatio'n ofiritensi'ty in the voltage. in.-

duced in. an actual windingcorresponding. to.v

winding 40A."

Startingagainwith the. north pole. of .rotor-2-4 to thele'ft as shown in Fig.1. and master. switch. B'IA .closed,..' the operator .can close. switch. lMAf. with..blade IDSagai'nst contact [2.2; and rotor. .24.

can then be. rotated J clockwise. through. .1809.

During the rotation, winding. 40A, is. illuminated byred light correspondingto sweep of. the rotor. north pole and windihgAflA'. is. illuminated lay.

green light corresponding to the. sweep of the rotor south pole, intensity of illumination varying ,from. zero at the start of the sweepto. amaximum and back to zerotagain atthe'end of.the-sweep. M The operator. can point out'fthat..the electrical. ef-

fects induced in actual. windihgs.corresponding.r to windings 40A andAOA are of. opposite polarity as indicated. by the. contrasting colorof light-ilelumination, and, that. irLorder. to connect the two windings so that. the effect. is additive, itisneces sary .to connect. them in seriesbutwiththewind ings in reversed relation to each other,. as. shown. byconductor 4.1 on cover-plate [8... The demon.-

stration can. then be continuedby rotating the.

training-aid rotor through. another .180 to com.- pletethe revolution; During theisecond, 180 of rotation, winding lllAis' illuminated with green light corresponding to the sweep of the rotor' south pole'andwinding '4 0A is illuminated'- with red light corresponding'to sweepof-the rotor north pole. Switch 56A closed against contacti86A by roller 61- at the start of. the rotor north pole. sweep'pastwinding 1051 24116113 'cl'osedagainst contact 31A by roller: 66' at the start ofathe. rotor south polosweeppast winding 48A.

Ordinarily, for" purposes of. demonstration,- switch-104A is closedawith-blades lll5.-and Il16- against contacts I02. and llz respecti-vely as-described above.whereby.--windings.4llA and 40A are:.illuminated...with.light of contrasting color.

to indicate that voltage. .of contrasting polarity is being induced inlthe two windings. If desired fon-purposoeofillustration, however, the color ofzlight-illuminationr for both winding 40A and WindingAlUA' can be made the same by closing. switch...l04A'. withblades I05 and I06 against contacts l 2 l and 1.03 respectively.

Illumination of :phase windings MB and 403.

can. be controlled likewise through master switch BlBandswitch I043. and illumination of phase...

windingswcand 409. can be controlled through master switch; 8 IC .and switch I a 40..

The various phase-windings can be illuminated.

individuallyes described, or, if desired, .all. of

the::windings. or any combination of windings can. bdilluminatsd, together by. proper operation. of switchesttA 8|..B, BICUandlMA", IMB' and] IMCC Instant conditionswwithin the windings of an...actualtgenerator can.be illustrated by anresting...rotor 24. .In this. manner, the instant. polarity and intensity ofinducedelectricalvolts age tin each winding areindicated by the color.

.tanddntensity of. light illumination of suchwinda. ing, and. the iinstant. relation between the various.

windings. ..1S--ShDWn.\

On thetother hand,..the progressively changing conditionssencountered in rotation. of an actual. generator: canzbeillustrated if. rotor 24 is turned thetconditionsimeach windingand the sequence... of) relations: between: the. ..various windings can.

be shown...

While eachwwinding, has been... .described. as.

having two sets-of, individually colored lights for. indicating polarityit is understood thatthe constnuction. can bemodifiedto use any desired num,.--

ber of difierentlyicolored sets, of: lights. for indieatingapolarityt or other.characteristics of the. induced electrical effectandthat suitable colors otherithamredsandgreencan be .used. A furthermodificationcan be made by usingvariation inithetintensity of illumination. toillustrate. variationaincharacteristics. of the induced. effect.

other than magnitude of induced .voltage.

Analternative :embodiment of the. invention.

shownrin Figs.8-to.1'6 inclusive embodies a mock motor-1.29 OfbthfiiiGllD-DOIB: type constructed so.

thatit canbe usedito simulate either a synchronous-type alternating-current..motor or an.- induction-typeaalternatingecurrent motor.

A- fr'ame' work-I30 including a box I31, having... top: I32, abottomr-t33- si-des I34 and aback I35 is--provided withparvertical reinforcing member l36 see Figs...8 &and 9 These :members can. be

made of wood or similar material. A cover-plate I31 isr-formed. fromv transparent. material such tie-Plexiglas. Box .I 3 t issupported upon vertical. legsl*38,-uwhich..are..reinforced by cross-braces. l3,9,.and-.-.each leg isvsecured by means of. anchor members ll40..to. a-platform. I41. supported upon. casters! 42, whichrender-theconstruction. movable;

Mounted.-.-for rotation in front of cover-plate I31 Iiig..13. .is. a disc I43 of. Bakelite or other.

opaque material which-issecured by a screw I44 prevents lateral displacement of shaft I48 relative to cover-plate I 31 of box I3I.

Mounted on shaft I48 between cover-plate I31 and back I35 is a pulley I53 having a peripheral groove I54 and a hub I55. A set-screw I56 locks pulley I53 to shaft I48 for rotation therewith. Pulley I53 can be made of wood or other suitable material. Mounted on shaft I48 in contact with the rear face of pulley I53 is a sprocket wheel I51 provided with peripheral teeth I58. Sprocket Wheel I51 is locked to pulley I53 by means of screws I59, whereby both sprocket wheel I51 and pulley I53 rotate with shaft I48. V

Mounted removably in front of disc I43 'is a second disc I60 having a central opening I6I, whereby disc I60 is fitted oversupport disc I45 against disc I43. by sliding clips I62,each of which is mounted for radial sliding movement under a bracket I63 Disc I60 is retained in place mounted on supporting disc I 45 by means of screws I64. When clips I62 are drawn radially inward toward each other, disc I60 can be removed from supporting disc I45. When disc I60 is mounted in place, clips I62 can be moved radially outward so that the extremities thereof overlap disc I60 to lock the latter in place.

Rotary disc I43 is designed to represent the rotor of an induction motor; while cover-plate I31 is designed to represent the stator of such a motor; Symbols (Fig. 8) representing peripheral slots I65 are painted or otherwise depicted on opaque rotor I43 for indicating that the rotori's of the conventional squirrel cage type used in in- I duction motors. An index I66 is inscribed on the face of rotor I43 so that during demonstration the relativeslippage between rotor I43and the rotating magnetic field of the stator, which slip; page is characteristic of polyphase alternatingcurrent motors, can be shown.

Removable rotor disc I60 is designed to represent the rotor of a synchronous motor having four poles. the poles of the rotor are inscribed on rotor I60.

Symbols representing electrical windings I68 are inscribed on rotor I60 and positive and negative symbols at the ends thereof represent relative direction of current. flow within rotor windings I 68; To simplify the illustration, the two opposed north magnetic poles are indicated by the letter N and the two opposed south magnetic poles are indicated bv the letter S; windings I68 and the pole s mbols afford a visual indication of the electrical and magnetic conditions that prevail in the four pole rotor of a motor of the synchronous type.

Preferably, transparent cover-plate I 31 is painted with opaque material such as black paint, except for symbols representing electrical v windings I69, which are designed to represent multiphase windings and which because of their transparency, can be illuminated by lights located within box I30 as hereinafter described.

other winding spaced 90 therefrom, indicated at I10A', to represent conditions whereby 'field Symbols I61 (Fig. 10) representing its 12 voltages of opposite polarity are impressed'upon the rotor pole windings of an actual motor. Similar windings I10B' and I100 are indicated. The two I10A windings and the two I10A windings are represented as being connected together in series with the I10A windings in'reverse re lation by conductors "I (see Fig. 8). The H013 and H03 windings and also the I100 and H00 windings of each of the other two phases are represented as similarly connected. The windings of the three phases are represented as con nected together in a manner conventional in actual motors of this type (see Fig. 8)

The three-phase windings I10A, H03 and I100 are adapted forillumination by a ring of lights I12 located within box I30, while windings.

I10A', H03 and I100 are adapted for illumination by a ring of lights I13 located within box I30. Alternate lights in each of rings I12 and I13 are red, while the lights in between are green. The'two colors are used to indicate the relative polarity of simulated induced voltage in windings I69. In a 'manner hereinafter described, red and green lights are arranged to be illuminated independently. The lights are mounted in individual sockets I14 secured to the inside of cover-plate I31. The inside of coverplate I31 is divided into individual. compartments by means of partitions I15, which are so designed that a separate compartment isplate I31 by screws I18. The'electrical connec-,

tions for illuminating lights I12 and I13 will be hereinafter described.

Mounted upon bottom plate I33 in one corner ofbox I30 is aSelsyn transmitter I19 (Figs. 9 and 14) of conventional type, which has a-forwardly extending rotor-shaft I supported by means of a bushing I80 mounted in cover-plate I31 and provided with a handle I8I'. Mounted forwardly of Selsyn transmitter I19 is a clutch I82 which will now be described.

The forward end of shaft I80 extends through an opening I83 in back plate I35. Mounted upon shaft I80 is a driving disc I84 provided with a set-screw I85 for locking the disc for rotation with shaft I 80. Driving disc I84 is provided with a forward friction face I86 and with a slot I81.

Mounted to the rear'of driving disc I84 upon.

ing a forwardly extending projection I92 that can be aligned with slot I81 in driving disc I84. Extending rearwardly from sprocket wheel I88 is an integral collar I93 provided with a channel I 94. Mounted forwardly of driving disc I84 upon shaft I80 for rotation relative thereto is a pulley I95 having a peripheral groove I96. Provided on the rear face of pulley I95 is a friction'facing I91. Extending forwardly from pulley I95 is a collar I98 provided with a channel I99.

Located above shaft I80 and parallel thereto is a clutch-shifting rod 20I provided with a knob 202 for manual manipulation. Rod 20I is supported at its forward end in cover-plate I31 by means of a bushing 203. Rod '20I is mounted so that manual reciprocation thereof can be effected; Mounted upon rod 20I V in proximity to pulley I95 is a shifting fork 204 having a bifurcated portioni5205.'i adaptedito ."seatfwithi'ncchannel I99 of pu1ley-c0l1arYI98h ShiftingrfbrkzZOt isi provi'dedfiwlth -an integral h'ub i 08,3 which is 1 Mounted uponrrod 20 I in proximity to sprocket Wheel 188 183, shifting fork Z08 provided with a bifurcated extremity- 209 adapted' to seat within L channel-I94 of sprocket -wheel hub 193i Shiftingz'lfork- 208 is provi'de'd with an integral huh ZI IL which is lockedto-rod 2M by means of A driVing' belt 2I2 (Fi'g. 13) connects pulley" wheel I53 mou-nted on shaft" I 48 and pulley wheel' Ni -mounted bn shaft I805- A"liiik chain= H3 intor-connects sprocket 'w-heel snart ma andi sprocketwheel I88mounted on shatt' 'IBU. The circumferenceof'pulley wheel I53 is2 A times that of pulley wheel IQSQwhilethe-circumference ofr sprocket wheel IE1 is twice The the circumference "of sprocket wheel- I88. manner'in-which clutch I82" may be operated to triansmit' drive from shaft" I8II"to'- shaft I48wi11 now be described.

With th'eparts of clutch I82" in the position shown'in Fig. 14, it wi-ll be seen that rotation of shaft l 80 rotates driving I di'sc I 84 3 while -pulley I95 and "sprccket=wheel' I88 are idling-on shaft I801? Under theseconditions shaft I48 does not rctatel If rod 2M is 'reciprocated to the right as seen in "Fig; 14, shiftinglfork 28'4" 'moves pulley Marta the right until frictiomface I9! thereof is; in'fengagement 1 with friction? face I I 86 of drivingcdis'cilflfl Und'e'rthese conditions pulley I95 istbrought graduallyirom idling up to the speed officlr'iving'di'sc I84 andshaft I802 Bymeans of be1ti2I 2, pulley I53 and ishaft I48 are brought gradda'lly to" a rotational speed of 1/225 the Under these conditions;

speed i of" shaft I 80.1 sprocket wheel I51} which is mounted 'for rotati'on with pulley I 55; is rotaltedgand through chain dlive 213' rotatessprocket wheel" I88, thereby simulating operation of 'aniind-ucti'on motor.

Tos'simul'ates 'conditions 'of operation of asynchi'onous 1. motor, rod 20 I is moved tothe left as SeenTiIi'JFig; 14, so "that pinvI flt'of sprocket-wheel IEBST- engageslinrslot IIBI ofdriving disc'I34 to loelcisprocket wheelFI88' and driving disc I84 to-- gethefiforrotationa Sprocket-wheel. I88 then rotatesmat "the; same speed" as r driving disc: I 84", andbymeans of: link chain 2I3 causes: sprocketwheel I51 and. shaft I 48 to rtateaat a speed cl? M213- the speed of shafti I801" The 'ratio" of rotational. speeds of shaft. I80, whichcarries the rotor of 'Selsyn transmitter? I 19',

and shaft 8,5 which carries synchronousdisc tweenrdisc I43 and the simulatedirotating electricalzfield. l

Selsyn transmitter 119 isproyided withra twopole rotor having a windingt2 I4 that; is connected by'means1 :of: conductors 412 I 5 and: 21-161 through a detachable connection-jack .2116; to LZCOIIdLlCtOI'S 13w; and-gr ll. respectively; of" rotor -windingr- I4, im'Selsyn transmitter "I 3. Seisyntransnntter I I9 furtheruprovided" with. stator phase windings conductor-1 I 6 of; :Selsyn: transmitter 113.; Stator I'5'I mounted on l; tactsx226, 221, 2218; and 229*are provided; on:

1431 Winding Z'I'B is; connectedzby "a conductorrfltntcc toggle blade 222' =0f double-pole 1 double-throw switch 223. Stator WindingxZISl-ds. connected by conductor:224 to'blade. 225 of switch 223. Conswitch223; Contacts 221 and228'are connected" by "a :conductor 230 fthrough, jacku 2Ii6' to'con. ductor I! or Selsyn transmitter 13 whilecontacts 226 and 229 are connected by 'a' conductor 231 through. jack 2I6 to conductor" 78 from Sels'ynatransmitter1'3: Blades 222 and 225' off switch" 223 are connected together mechanically by axtierod 232 "so that movement in unisonicanl be-efiected:

Itrwillfbe seenvthat when blades 222landt25n arethrovmrto' the right against contacts 221: and 229 respectively, Selsyn H9 is connected toselsync; I3 :so that the rotors ofxthe two Selsyns rotate infithessamedirection. If blades 222 and 2250f" switch 223 are thrown: to the left againstcona tacts 226" and '228,' connections from'isel'syn I3 tozfstator windings 2I8 and J2I'9are reversed fso that the direction of rotation of: the rotors of Se1SynsT3 and I19 isopposite.

The circuit forzilluminating the .red lights 'of" windings IIIIJA and'the green lights of windings I'IBA" will: now'be' described; A conductor "233" is connected" at one end i'through jack" ZIE to COHtQLCtTB Q A Of sWitch't54A* (Fig-l7) and at its other'end is connectedto: contacts" 2.3'4-anctfi21i5- of: at double-pole double-throw switch.- 236. Switch 236' is provided with. another pair of contacts i231 and 238 and::is further .provided with toggle-blades 239I5and 246, which are' linked me chanically by'tietrod '24 Knife blade 2391510011- nected by means of a conductor 242 to a feed line243a' for a set: of-red'lights' 244A, which: serve to "i1'1uminate winding, I'IIJA, and greenalightslr 245A, whichvserve .to illuminate-winding I 'IIJAE Aireturn line 24'6f'is connected by means'of. a: conductor: 241 to-knifeblade 222 of switch 223.-

Contacts 231: and 238 offswitch 236-arec0n-- nected by a conductor "249 throughrjack 2 Hi to: contact flfiB 'of switch- 5413 '(Fig. 7). Blade-240: ofvswitchi23'is":c0nnected by conductor 250 to a-feed line 25.1 forred lights 252B,which'illumi nate winding ilfiB and green light 25353, which illuminate winding I'IQBC' A return 1ine-254 is connected through. a conductor 25% to knife blade 225-of-switch 223.

Av'conduc-tor, 2591's connectedat one end throughr jack'2I6 to contact 8600f switch 540 and" atits other endrisconnected by means of feeder line 260: torred lights-26 I-G; which illuminate winding I'IIBC, a-nd greemlights 2626', which illuminate wind-- ing INC. A return line 263 is connected through a :conductor' 2 54, to-=conductor 2 2 0.

A conductor 265" is 4 connected at. one; endthroughjack 216 to'contact 81A-oi switch 5th (Fig.7) and: at its other endis connected to contacts ZBBand 261' of adouble-pole double-throw switch'yzfill. A pair of contacts 269 and 210, together with toggle-blades 211- and 212, complete" the switch: Atie'rod 213 links blades 2'II and:

'- 21'2 mechanically to provide movement in unison;

thereof; Knife blade'z'l'i is connected'byacon-- ductor "214 through feeder-line 215 to greenl'lights 216A, whichr illuminate winding A; and red; lights 2111A", which illuminate winding. I'IIJA".

A: return dine-i218 connects' toa conductor 219i;-

WhiChiS connected to'conductor 241.-

Tie :rods 2.4 l of swi'tch236; 2321 of switch 223 and 213 ofiswitch2fi8 are interconnected mechanicallytfor movement in unison'by aiinkz-248L;

A conductor 219 is connected at zonezrendt through jack 2H5 to contact 81B of switch. 543

and at its other end is connected to contacts 269 and 2H}- of switch 268.

Blade 212 of switch 268 is connected by a conductor 286 through a feede line 28] to green lights 28213, which illuminate winding HEB, and red lights 283B, which illuminate winding HUB. A return line 234 is connected through a conductor 285 to conductor 255.

A conductor 2% is connected at one end through jack 256 to contact 81C of switch 540, and at its other end is connected through a feeder line 281 to green lights 2880, which illuminate winding NBC, and red lights 2890', which illuminate winding NBC. A return line 296 is connected through conductor 29! to conductor 264 and conductor 22H.

The wiring diagram described is designed so that by means of detachable jack 2l'6' the circuit used for illuminating mock motor I29 is controlled through master switches 85A, 8:3, MC and selector switches MA, MB and 54C, which are mounted upon mock generator It! described in connection with Figs. 1 to 7. In Fig. 16 is shown a wiring arrangement for use in connection with the lighting system disclosed in Fig. 15 whereby the lights used to illuminate mock motor I25 are controlled through master switches and selector switches mounted in association with mock motor 529 itself so that it can be operated independently of mock generator l0. Construction. of the master switch and selector switches disclosed in connection with Fig. 16 is identical with those disclosed in connection with Fig. '7, and only a schematic showing thereof is made in Fig. 16.

As seen in Fig. 16, conductor 233 is connected through jack M6 to a conductor 2532 and contact 293A of selector switch 29 2A, which has a second contact 295A and toggle-blade 296A. Conductor 249 is connected through jack 2ft to a. conductor 29?; which is connected with contact 2933 of selector switch 29 B, which has a second contact 295B and a toggle-blade 296B. Conductor 259 is connected through jack 2l6' to a conductor 298, which is connected with a contact 2930 of switch 2940, which has a second contact 295C and a toggle blade 2960.

Conductor 265 is connected through jack 2l6' to a conductor 2% and to contact 295A of selector switch 294A. Conductor 219' is connected through jack 2% with a conductor 300, which is connected to contact 295B of selector switch 2945. Conductor 28B is connected through lack 21s to a conductor 384, which is connected to contact 2950 of switch 2940.

Conductor 22B is connected through jack 256" to conductor 382 and knife blade 303A of master switch 304A which has a contact 395A. Contact 395A is connected by means of a conductor 306 to knife blade 295A of selector switch 294A.

Conductor 230 is connected through jack M6 to a conductor 30'! and knife blade 363B of master switch 30 23, which has a contact 3053. Contact 305B is connected by means of a conductor 36% with toggle-blade 2963 of selector Switch 2943.

Conductor 23! is connected through jack 2E6 to a conductor SE19 and toggle blade 333C of master switch 3116C, which has a contact 3050. Contact 3550 is connected by means of a conductor 3m with toggle-blade 295C of selector switch 294C. Conductors 2E5 and 2H; are connected through jack 2H5 to any suitable source of alternatingcur'rent for exciting Selsyn rotorwinding 2M.

Selector switches 294A, 294B and 294C are. arranged so that rotation of main shaft MB of.

the simulated motor will cause actuation thereof to control illumination of the lighting arrangement disclosed in Fig. 15, and in this respect, operation of selector switches EMA, 2%}; and 2940 is identical in operation with selector switches MA, MB and 5 30 described in connec-' tion with Fig. 7.

tical with master switches A, 85B and 8lC disclosed in connection with Fig. 7.

Operation of mock motor E29 will now be described. In startin a demonstration, synchronous rotcr disc see is removed to expose induction disc M3. Clutch knob 2E2 (Fig. 14) is placed in neutral position so that driving disc E34 is out of contact both with pulley E t5 and sprocket wheel E88, as shown in Fig. 14. Jack. Zit' '(Fig. 15) is then connected with mock generator l8 as described previously, so that selector switches 5AA, MB and 54C, together with master switches.

86A, 89B and MC control illumination of lights I12 and H3 in mock motor E29. Wires (3 and '84 from Selsyn rotor winding iii are connected to a suitable source of alternating current.

Energization of windings can then be demonstrated by turning handle 65 (Figs. 1 and 2) to cause rotation of Selysen rotor it through 90. As red lights Z MA are illuminated to maximum brilliancy, green lights 255A are illuminated to maximum brilliancy, indicating that windings HQA and Him and all other windings'are being energized in opposite polarity. Rotation of Selsyn rotor i l through an additional 90 causes red lights Z-ttA and green lights 24 51 to diminish in brilliancy and to be succeeded'by illumination of 1 green lights 275A and red lights Zl l'A. lhus, as

Selsyn rotor M is turned windings iifiA and I IOAf and all other windings are illuminated in such sequence that there appears to be a rotating field.

Since the order in which the lights behind the different windings reach a maximum intensity determines the apparent direction of rotation of the field, such apparent rotation can be reversed by reversing the order in winch such 'illumina This can be effected by reversing double-pole double throw switches 23%, 268 and 223 (Fig. 15), which move in unison under the tion occurs.

influence of tierod 248. 7

Operation of an induction motor can be il-' lustrated as follows. The starting of an induction motor can be demonstrated by rotating Selsyn rotor M that in turn rotates Selsyn I19 at any suitable speed and reciprocating clutch-knob 202 (Fig. 14) to the right to bring friction facing l9! of pulley'l95 into contact with friction facing I86 ofdriving disc I84. The speed of rotation of pulley 595 is increased graduallyfrom zero to approximately the speed of rotation of driving disc i 84 and by means of belt 2l2 causes rotation of pulley 53, main shaft H58 and induction disc M3 to a speed of about 90% of the Master switches 394A, 3043 and 304C disclosed in Fig. ldare adapted for manual operation and in this respect are iden- Rotation of synchronous-motor disc is efiected in the manner just described while his explained in the demonstration that a syn-.=

atlases 17., chronous motor has nostarting torque and actually it is required that some other means of starting be provided. It is explained during the demonstration .that by energizing rotor windings I68, definite poles are established, and said poles are repelled or attracted by poles in the rotating field so that the rotor operates at the same speed as the rotating field. This condition is demonstrated by rec'iprcatiiig clutch knob 202 to the left as seen in Fig. 14 so that pin I92 seats within slot I81 to leek-sprocket wh'eel I38 to driving' disc I84 and cause-the same rotation thereof. By means of sprocket-chain 2I3; rotation Of sprocket wheel I51, main shaft I48 and synchronous-motor disc I60 is effected at the same rate of rotation as the rotating magnetic field.

Since mock generator I!) is in operation during demonstration of mock motor I29, the combination simulates operation of a generator and a motor together, and the characteristics thereof can be explained during the demonstration.

Should it be desired to operate mock motor I29 independently of mock generator I0, jack 2I6' is disconnected from mock generator I and connected as described previously in conjunction with Fig. 16 Under these conditions, rotor 2| of Selsyn H9 is connected by conductors 2I5 and 2I6 to a suitable source of alternating current. Selsyn rotor 2 I4 can be turned by means of hand crank IBI (Fig. 14) to effect rotation of both main shaft I48 and illumination of lights I12 and I13.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In combination, a mock device for simulating interconverting mechanical and electrical energy comprising a pair of members mounted for relative movement, simulated electrical windings on said members, electrical means synchronized with said members for illuminating said windings upon relativemovement of said members; asecond mock device similar to said first mock device; means interconnecting said mock devices for synchronous actuation of said members; and electrical means whereby said devices can be operated together with one of said devices simulating a generator and the other of said devices simulating a motor of a motor-generator set.

2. In combination, a mock generator comprising a simulated rotor, a simulated stator, simulated electrical windings, electrical means synchronized with said rotor for illuminating said windings to simulate an induced voltage therein upon rotation of said rotor; a mock motor comprising a simulated rotor, a simulated stator, simulated electrical windings, electrical means synchronized with said rotor for illuminating said windings to simulate an electrical voltage for causing movement of said rotor; means interconnecting said rotors and said electrical means for synchronizing movement of said rotors and illuminations of said windings so that said mock generator and said mock motor can be operated together to simulate a mock generator-motor set.

3. A mock electro-mechanical simulated interconverter comprising a rotor member, a stator member, means in one of said members simulat- 18' ir'ig electrical winding-s; means for illuminating said windings, and electrical means synchronized withsaid other member ror varying the intensity or said illumination to simulate Variations in the instant intensity or electrical energization of said w ndings.

I 4. ni'ocx electro mecha-nical simulated intercohverter comprising a rotor member. a stator member, siii'lulated electrical windings on one or said members, means adapted for illumination 01' saidwlndlngs, a belsyn transmitter syncmoii ized with said rotor to vary the intensity or said illumination to simulate variations 1n the instant intensity oi electrical energizatfo'n or said windings; and means Ior varying color or illumination to simulate variation in instant direction or shrill-'- lated current now.

5. A mocl; multiphase electro-mechanical simulated inter-converter comprising a rotor member, a stator member, simulated phase windings on one of said members, a set 01' colored lights for illuminating each phase winding to indicate instant now of current in one direction, a second set of difierently colored lights for illuminating each phase winding to indicate mstant now 01 current in the other direction, a Selsyn transmitter synchronized with said rotor to vary the intensity of illumination in each phase winding to simulate variations of intensity in current how in said windings corresponding to different instant positions of said rotor, and electrical switches synchronized with said rotor for selecting automatically the set oi colored lights for illuminating each phase that corresponds to the instant direction of simulated current now.

6. A mock multiphase generator comprising a rotor member, a stator member, simulated phase windings on one of said members, a set of colored lights for illuminating each phase winding to indicate instant flow of induced current in one direction, a second set of differently colored lights for illuminating each phase winding to indicate instant flow of induced current in the other direction, a Selsyn transmitter synchronized with said rotor to vary the intensity of illumination in each phase winding to simulate variations of intensity in induced current flow in said windings corresponding to difierent instant positions of said rotor, and electrical switches synchronized with said rotor for selecting automatically the set of colored lights for illuminating each phase that corresponds to the instant direction of simulated current flow.

7. A mock multiphase motor comprising a rotor member, a stator member, simulated phase windings one one of said members, a set of colored lights for illuminating each phase winding to indicate a voltage of one polarity, a second set of differently colored lights for illuminating each phase winding to indicate voltage of opposite polarity, a Selsyn transmitter synchronized with said rotor to vary the intensity of illumination in each phase winding to simulate variations of intensity of voltage in said windings corresponding to different instant positions of said rotor, and electrical switches synchronized with said rotor for selecting automatically the set of colored lights for illuminating each phase that corresponds to the instant polarity of said voltage.

8. In combination, a mock generator comprising a simulated rotor, a simulated stator, simulated electrical windings, electrical means synchronized with said rotor for illuminating said windings to simulate an induced voltage therein upon rotation of said rotor; a mock motor com- 

